PilotChris

Isn't the compressor supposed to cycle on and off when the A/C is on? My compressor runs constantly! My A/C is pretty cold, but I'm starting to second guess myself after seeing my compressor isn't cycling. I put a thermometer in the vent, turned it on MAX cold, and let it run for 10 mins with the passenger door 1/2 way open. After 10 min the thermometer read around 50F.

Anyone have any advice about this?

Thanks,
-Chris

xviper

50 degrees is considered normal IF the outside temp was about 85*F and the humidity was around 20%. Simply getting a reading of 50*F by itself is not an indication of how your system is doing.
How do you know it is on all the time? The compressor clutch cycles on and off and you may not know when this happens. Also, another tell tale hint that the A/C is running all the time is if the second rad fan is also going all the time as this one is tied into the A/C. But if it is indeed running all the time, then no, this is not a usual situation.

Slows2k

The compressor will cycle, but for how long and when is determined by the position of the temp knob, and the Evaporator temp sensor.

It's not going to blow ice cubes out with the door cracked. To check the vent temp, ther blower has to be on high, recirculate must be selected, and temp at max cold. Even then it can take 10-20 minutes to reach the coldest temp. expect to see around 42-45deg. F.

As far as the fan controls go, both cooling fans are designed to run with the AC on. Both fans run as well when the cooling fan switch in the radiator is closed.

If the air temp still feels cold, Don't worry about it.

PilotChris

Ok thanks guys. Yes I've watched the compressor and radiator fans and they never cycled over the course of about 20 min. It will cycle if I hold 3k RPM for a few minutes, but never does it at idle. I may just take it to an A/C shop just to get it checked. If it's just freon then I'll get it added, if it's anything more, time to use that extended warranty

Thanks again

Gregg Lee

[QUOTE]Originally posted by PilotChris
Ok thanks guys.

xviper

On my car, I have witnessed only one rad fan running. I can cause the second fan to come on when I activate the A/C.

Slows2k

Xviper, I don't think the Canadian cars are wired any different, But the US spec cars run both fans with the AC and both fans when the fan switch in the radiatior is closed.

xviper

Maybe it's because we have a generally "cooler" climate.

Slows2k

Maybe it's the daytime running lights. Or you have a flakey condensor fan motor.

bdo

Ok, this is somewhat late but I just saw the thread, and I like to think I know a thing or two about A/C.

As others said, as long as your AC is working okay and cooling the car, it may not be worth worrying about or spending money on at this point. If the car is not moving, the compressor runs more because no air is being forced through the condensor.

OTOH, it doesn't sound right for the compressor to run non-stop for 20 minutes. Were you watching the compressor itself or just the fans?

Also worrisome is your 50 degree reading. On most cars, with the AC on max (recirulate), low to medium fan, and the heater valve all the way to cold, you should be getting more like 40 degrees and possibly a little lower. What was the weather like when you took this measurement? Were you in the shade? As xviper said, hot weather can affect what is "normal," but 50 degrees still sounds high to me.

I have to disagree with Gregg on his point that the "A/C compressor is unlikely to ever cycle at 0 mph at idle" and "everything you have observed is absolutely normal." Generally the compressor should cycle even at idle, although it may be running more often than not. He's right that the evaporator would freeze over if the compressor were not cycling on an otherwise-working system, but you have the opposite problem. It's never getting cold enough to need to cycle off. And it should, unless you're in the sun on a relatively warm day.

Taking it to a good A/C shop can't hurt. Please let us know what you find out. Realize, though, that the problem is not "just freon." If your 2-year-old car is low on freon, then there is a leak somewhere that should be fixed. Being low on freon after 2 years is not typical. (And it technically isn't freon; it's R-134a, which replaced R-12 aka Freon. But that's just semantics.)